1. Field of the Invention
The present invention relates generally to the machining of a spline shaped workpiece. In particular a free form cutting machine that simplifies the machining of the spline shaped object is described.
2. Related Art
Machining is a process by which pieces of material are mechanically cut to achieve a desired geometry. Milling machines, lathes, and drill presses are commonly used to machine materials such as wood, plastic, and metal into objects with geometries requiring a high degree of precision. A conventional turning machine (the most common embodiment being a lathe) typically utilizes a single edged cutting tool to shape a workpiece. A typical configuration includes a spindle which rotates the workpiece that is then engaged by a cutting tool. The cutting tool position can be moved closer or farther from the rotating workpiece, but the cutting tool orientation is typically set to a fixed angle. Unfortunately, while this configuration works quite well for machining a cylindrically shaped workpiece, a more complex shape is more difficult. Because the cutting tool orientation cannot be adjusted while it cuts, a non-cylindrical workpiece will change the angle between the workpiece and the blade as it turns.
For example, using this configuration to machine a spline shaped workpiece, would result in what is commonly referred to in the industry as a crash. The turning machine cutting tool crashes when a flank portion of the blade (essentially the bottom face of the cutting tool) comes into contact with the workpiece surface. The cutting tool is typically designed to operate with a relief angle between the flank portion of the cutting tool and the workpiece surface. The relief angle ensures the only portion of the tool in contact with the workpiece surface is a single cutting tool edge of the flank (essentially the forward edge of the flank). A crash will typically occur as the cutting tool tries to cut around the rounded corners of the workpiece. The orientation of the cutting tool with relation to the workpiece surface changes too much reducing the relief angle to zero and putting the flank of the cutting tool into contact with the workpiece.
Therefore a machine that allows for the creation of complex geometries in a single pass is desired.